How can I convert the probability score between 0 to 1 to another format?
You could maybe do something like this, it's a bit hackish
\begin{equation}
y = C_1\cdot 1 + C_2 \cdot 0.5 + C_3 \cdot 0
\end{equation}
$y$ represents the output and its bounded $\in [0, 1]$. $C_i$ is probability for class $i$. This way when $C_1 \approx 1, C_2 \approx 0, C_3 \approx 0$ you have
\begin{equation}
 y \approx 1\cdot 1 + 0.5 \cdot 0 + 0 \cdot 0 \approx 1
\end{equation}
when $C_1 \approx 0, C_2 \approx 1, C_3 \approx 0 $ you have
\begin{equation}
 y \approx 1\cdot 0 + 0.5 \cdot 1 + 0 \cdot 0 \approx 0.5
\end{equation}
and when $C_1 \approx 0, C_2 \approx 0, C_3 \approx 1 $ you have
\begin{equation}
 y \approx 1\cdot 0 + 0.5 \cdot 0 + 0 \cdot 1 \approx 0
\end{equation}